Immobilization of β-glucosidase onto silicon oxide nanoparticles and augment of phenolics in sugarcane juice.

Purified β-glucosidase was immobilized on SiO2 nanoparticles with 52 % efficiency and 14.1 % yield. It had a temperature optima at 60 °C and pH optima of 5.0. Immobilized enzyme was fairly stable at 60-70 °C. After immobilization, the Km value of β-glucosidase for p-nitrophenyl-β-d-glucopyranoside (pNPG) increased from 0.9 to 1.074 mM and Vmax decreased from 3.5 to 1.513 U/mg. The immobilized enzyme showed improved storage stability at temperature 4 and 25 °C and was reusable for up to ten cycles with 70 % residual activity in pNPG and 60 % residual activity in sugarcane juice treatment. Sugarcane juice density, viscosity; surface tension etc. changed after treatment with immobilized β-glucosidase. β-Glucosidase treated sugarcane juice showed higher phenolics than untreated sugarcane juice. Caffeic acid which was absent in juice, was detected in β-glucosidase treated juice at a concentration of about 1 mg/L.